Most recent update anywhere in this site other than notes of progress in
linked sites - 12/5/2014. Most recent new link or update on linked sites
elsewhere noted here to have come into existence - 9/25/2014.
Linked sites are likely to get updates before I next note them.

CAUTION (7/13/2012): this site describes open source hardware and has open
source software. Please read my disclaimer.

Look here for hints and ideas for electronic and other hobbyists, as well as
some lighting related info that you might find useful or at least interesting.

You may want to come back here every few months. This site is always under
construction!

I have an LED Main Page. (updated 12/5/2014, some
external links noted as updated 9/25/2014.)

Don's Lighting Info Center, go here to see lots of
information about many forms of lighting.
Here you can find basic and advanced theory, other stuff including
troubleshooting and repair hints. Lots of info on incandescent, halogen,
fluorescent, compact fluorescent, HID lamps such as mercury, metal halide,
high pressure sodium, and short arc lamps!
Also info on neon, low pressure sodium, oddballs such as green neon lamps.
Even a bit on UV lamps, night lights, lightbulbs lasting a century, electronic
ballasts, and carbon arcs. Also better info on lamps for growing plants.Added 2/15/2010 - s/p ratios of many light sources!
(updated 8/3 - 12/5 2014)

Don's Laser Top Page.
Ways to hack some cheap laser pointers to obtain boosted power (anywhere from 7
to 30-plus mW) that makes them dangerous and illegal to use as toys! Links to
where to get dangerous 15 to 190 milliwatt green laser pointers and 1-watt blue
ones as visible as 60-800 mW red lasers would be! NEW - orangish-yellow laser
pointers, blue ones, violet ones! Also stuff on He-Ne lasers and more. This
includes how to make a UV laser whose lasing medium is air at low-altitude
atmospheric pressure, which Ben Franklin could have built - but pre-1960
manmade lasers have yet to be recorded.
(most recent update unrelated to Sam's laser FAQ 5/23/2014, links to V. 14.50
of Sam's Laser FAQ 3/5/2014 and Craig Johnson's laser stuff 4/16/2014)
For links to unmodified official versions of Sam Goldwasser's Laser FAQ,
most of them leading to V. 14.5 (current as of 5/23/2014\) and none older
than V. 9.10 (current as of 3/23/2009), as well as the V.9.10 .zip version,
go to my above Laser Page.
(35-plus meg of good stuff, plus over 350 GIFs and JPEGs as of V. 13!)

Don's Tesla Coil page! (No news since 9/22/2008 as of
11/27/2013)
Includes some nice stuff on Tesla coils in general and on solid state Tesla
coils. Submitted to the Tesla Coil Web Ring 10/17/99 (though I have since
incurred a failure to be in that webring. New page added 8/27/2001 and this
section had a major update on 9/22/2008 (first in 2 years)! Progress continued
slowly on one of a few previously noted largish solid state Tesla coils until
being backburnered in late 2008. Links added to other sites with working coils
and working schematics 7/5/2005.

Check out my High Voltage Generator Page for a few
circuits to get thousands of volts from low voltage DC.
(Latest update a minor one 3/22/2011.)

Even more things now, like Jacobs ladders, plasma spheres, neon lamp
oscillators, etc. To find out how these work and how to make these,
go here! (Latest update a minor one 9/23/2008)

Spectra online! Visible line spectra of various
elements and a few common light sources. (15 spectra plus a wavelength scale as
of 7/4/99, link added to another site 7/4/2005.)

Now lighting and color as far as stars are concerned is here. Although for
now concentrating on Gliese 581, and specifically
theoretically on that red dwarf's discovered-in-2007 "earthlike" planet.
Updated 1/2/2011.

NEW! Hints to make your PC run faster.
Includes Dan Barclay's patch to blazingly improve math coprocessor usage
by Quick Basic 4.5 and other Microsoft programming languages. Also how
to get higher math speed by compromising the math coprocessor precision in
some C compilers! Also simple stuff like more memory, registry cleaning,
and some fairly-easy-and-safe manual registry editing and tweeks!
(updated 1/14/2013, most pre-2005 stuff is moved to a linked page.)

Download Dan Barclay's math coprocessor patch from
here to greatly speed math coprocessor usage by some Microsoft programming
languages, especially Basics (such as Quick Basic 4.5 and Basic 7 / QBX and
possibly some versions of Visual Basic and maybe some C and C++ products) and
executables produced by these programming languages. This is a zip file with
the patch, and lots of usage instructions and hints by the patch author and
also by me. Math speed is usually doubled to tripled, sometimes more.
This may apply mostly only to some pre-2000 Microsoft programming languages or
"programming environments".

There is now loudspeaker stuff here. Already here:
Plans to get big sound from a cheap 5-inch fullrange, and amazing lower
bass from a Radio Shack 10 inch woofer at home or in a car with a trunk.
Also: Plans for very cost-effective bass bins, also how to make piezo
tweeters sound more natural. Just added: Mad ideas based on the unimportance
of frequencies below 600-800 Hz to the intelligibility of the human voice. Get
more apparent voice PA power with 70 percent less amplifier power!
(Slight update 6/19/2011 but progress here is low since before 2008)

As of now, DOS executables are available for all programs available here
and BASIC source code is posted for all freeware available here.
Requirements are usually a version of DOS absolutely minimum of no more than
2.3, preferably 3.0 or higher, normally available under Microsoft Windows
3.anything, 95 and 98. Windows XP "Command Prompt" at least generally works
with these. Some programs require VGA or compatible display (the usual
nowadays since 1994 or so).

Number of programs available as of 1/2/2011: 3 freeware. Two deal with
blackbody radiators, especially for lighting. The 3rd is a highly improved
loudspeaker enclosure one using Thiel-Small parameters and enclosure
parameters to predict on-axis frequency response, after many real-world
factors.

Links to other sites I consider worthwhile:

Sam Goldwasser's site at repairfaq.org!
The laser, strobe, and fluorescent lamp documents that are mainly of his
authorship can be found there as well as here. Also tons of other
electronics repair and electronics stuff!

Dozens of significant elections decided by margins of
51-49 and even just a few votes, and one by a large margin but with turnout
so low that the losing side had a chance to win their battle of the century in
Houston. You might have voted in one of these or sat out one of these! Effects
of elections as far back as 1985 persist today! With many razor-thin results
including but also besides the 2000 presidential election! Even 2000 state
results for President close other than the Florida battle. My home state
usually has legislative majority by a party of only 1-3 seats and maybe once a
decade a legislative seat is decided by fewer than 100 votes! In 2006, 23 votes
determine party majority of one house of PA's legislature! In 2006, .3% of
VA voters give the Democrats a majority of the US Senate! U.S. House seats get
decided by a couple hundred votes or less twice in the past two decades - and
in this time a significant tax bill passes by one House vote!UPDATE 12/4/2006!